Conveyer shaft counterbalancing and indicating apparatus



March 11, 1952 s. M. MERCIER CONVEYER SHAFT COUNTERBALANCING AND INDICATING vAPPARATUS Filed Nov. 25, 1946 4 Sheets-Sheet 1 ,IIS

[N l/EN TOE 5TANLEY M. MERGER,

March 11, 1952 Filed Nov. 23, 1946 s. M. MERCIER 2,588,864 CONVEYER SHAFT COUNTERBALANGING AND INDICATING APPARATUS 4 Sheets-Sheet :2

Fig. 2

f/v vE/vTo/Q STANLEY M. MEECIEE) 4 Sheets-Sheet 3 S. M. MERCIER CONVEYER SHAFT COUNTERBALANCING March 11; 1952 Filed Nov. 25, 1946 Patented Mar. 11, 1952 CONVEYER SHAFT COUNTER-BALANCIN G AND INDICATING APPARATUS Stanley M. Mercier, Bexley, Ohio, assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Original application September 1, 1943, Serial No.

500,799. Divided and this application November 23, 1946, Serial No. 711,910

4 Claims.

This invention relates to elevator or conveyer mechanisms and particularly to mechanisms for counterbalancing weight and indicating the position of a bodily movable or floating shaft of an elevator or conveyer mechanism over which a traveling conveyer element operates, such, for example, as the traveling chain and bucket elevator mechanism of a hot catalyst elevator.

It is an object to my invention to provide in an elevator or conveyer having a shaft adapted to carry floatingly a conveyer element, an improved mechanism for limiting floating movement of the shaft to an upright plane and for counterbalancing at least a portion of the weight thereof wherein the counterbalancing mechanism includes an overbalanced frame carrying the shaft and pivoted about an axis movable in a plane intersecting the upright plane of movement of the shaft whereby the frame follows the floating movement of the shaft.

It is another object of my invention to provide an improved mechanism for carrying a floating shaft of an elevator or conveyer that is limited to up and down movement in a plane, the mechanism including an overbalanced frame pivoted to the shaft and pivoted about an axis parallel. to the axis of the shaft and movable in a plane intersecting the plane of movement of the shaft.

It is another object of my invention to provide in a conveyer having a bodily movable or floating shaft an improved means for restraining movement of the shaft to an upright plane, the means including an overbalanced frame adapted to sup port at least a portion of the weight of the shaft.

It is still another object of my invention to provide an improved conveyer having a housing and a foot shaft mounted therein for up and down floating movement wherein the foot shaft is carried at its opposite ends by the frame mounted for up and down movement and wherein there is an indicator outside the housing indicating the position of elevation of the frame and foot shaft.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings,

Fig. 1 is a side elevational view of an elevator or conveyer incorporating the features of my invention;

Fig. 2 is a view on a larger scale of the bottom portion of the elevator or conveyer shown in Fig. l;

Fig. 3 is an enlarged sectional view taken through the foot section of the elevator or conveyer, with parts omitted for the sake of clarity, the view being taken on line 33 of Fig. 2;

Fig. 4 is an enlarged sectional elevational View through the axis of the foot shaft of the conveyer, showing one end of the foot shaft and associated structure; and

Fig. 5 is a sectional plan view showing one end of the foot shaft and associated apparatus, the view being taken substantially at right angles to the view of Fig. 4, no attempt being made in this figure to show the foot wheel and associated insulating material.

This application is a division of my application Serial No. 500,799, filed September 1, 1943, for an elevator, now Patent No. 2,491,899, dated 'December 20, 1949.

The conveyer or elevator illustrated as a whole in Fig. 1 of the drawings is very large and is adapted to convey hot material, such for example as hot catalyst used in the cracking of petroleum. The conveyer includes a vertical or upwardly extending tower or main frame 20, which main frame 29, as viewed in cross-section (see Fig. 3) is rectangular in shape and each of the four corners includes a vertical or upright structural member, such as a channel 2 I. Each of the channels 21 in the finally assembled condition of the main frame 2!! constitutes a continuous upright member which extends from the foot or bottom of the main frame 20 to the top thereof. At their bottoms the channels 2| are provided with feet 22, preferably rigidly attached to base members which may, for example, be mounted on a poured concrete base sunk sufficiently in the ground to provide a firm foundation. At their tops the channel members 2| are rigidly connected together by side I-beams 23 and cross channels 24 which cooperate to form a platform for supporting a motor and other parts of the conveyer or elevator.

Along each side of the main frame 29 the front and rear channel members 2| are connected by diagonal braces 25 as well as by spaced horizontal angle braces 26. The front vertical channels 2! and the rear vertical channels 2| are connected by moment connectors in the form of spaced plates 21 (see Figs. 1, 2 and 3). Plates 2'! connecting the front vertical channels 2| are directly opposite the plates 2'! connecting the rear vertical channels 2| and these plates are preferably vertically spaced on their respective channels a uniform distance apart. In one installation of the conveyer or elevator shown the vertical distance between the moment connectors 2? was eight feet.

The main frame or tower of the conveyer is an independent self-supporting structural unit that acts as an outside support for a sectional housing or casing 40 and it cooperates therewith to form a complete housing structure connecting a head section 4! and a foot section 4? of the conveyer. Because main frame or tower is is entirely outside the elevator casing and removed from the influence of high temperature within the casing it is free from major thermal stresses and strains.

Mounted upon the I-beams 23 at the top of the main frame 29 is a pair of spaced bearing boxes 29 that support an internally cooled horizontally extending head shaft 38 which carries a head support assembly 3|. The head support assembly 35 includes a pair of spaced sprocket wheels 32 which operate with and drive a pair of spaced endless chains 33 of a bucket elevator or conveyer mechanism 34. Shaft 36 is provided at one end with a drive sprocket H5 which is keyed thereto and at the other end it is provided with a brake wheel Ill with which a mechanically operated brake device H8 cooperates. Drive sprocket H5 is driven from a motor and speed reducer mechanism H9 carried upon the platform formed by channel members 23 and E i through an appropriate chain and sprocket or equivalent drive I20.

The head section 4! includes the part of the casing or housing associated with the top portion of the conveyer or elevator and this section includes a discharge spout 42 and a .totally enclosing hood that covers the head sprocket assembly 3!. The entire inner surface of the enclosing hood and in fact most of the inner surfaces of the other sections of the casing or housing are covered by a thick layer of insulating material that is preferably formed of slabs of compressed molded insulating material of high insulating character bolted to the surfaces. 7

At the foot or bottom of the tower or main frame 2!] there is a foot shaft 37 which is de-' scribed more completely hereinafter. For the moment it may be pointed out that the foot shaft 31 is part of .a foot shaft assembly 38 that includesa .pair' of spaced traction wheels 39 and is mounted for free or floating guided vertical movement within the foot section ll of the housing or casing.

Each of the two chains 33 of the bucket elevator mechanism 34 operates over one of the head sprocket wheels 32 and one of the traction wheels 3?; of the foot shaft assembly 33 and the chains carry between them a plurality of material carrying buckets 35 (see Fig. 3) which are rigidly attached adjacent their sides to the inner sides of the chains 33 by appropriate brackets or attachments 36.

A plurality of intermediate casing or housing sections El'which are generally of similar construction cooperate to connect the head and foot sections d! and M, respectively, and these sece tions form the principal portion of the housing or casing 46 insofar as actual height is concerned. The structure of a typical intermediate section 61 includes one pair of the horizontally aligned plates or moment connectors 2? carried by the front and .back vertical channel members 21 of the main frame 2e and a pair of side plates, not shown, which are spaced inwardly of the side'pairs of channels 2! and their connecting braces 25 and 26. These plates are connected at their ends to the plates or moment connectors 21 and cooperate with the latter to form a rectangular circumferential belt supported by the main frame 20 entirely surrounding the conveyer 34 and having its opposite side members spaced inwardly from the side channels 2| of the main frame. The inner surface of the belt is covered by a belt of insulating material formed of four separate slabs of insulation, each of which is bolted to one of the plates thereof. As previously mentioned the plates or moment connectors in one installation of the elevator were spacedeight feet apart and therefore in that installation there was a belt such as described at eight foot increments in height of the main frame 20.

There are front and rear panels 12 and two side panels 13 in each of the intermediate casing or housing sections 6? and each of these panels is rigidly connected at its center adjacent its top edge to one of the plates of said belt. The panels 12 and 73 are connected at their sides edges and cooperate to form a rectangular tubular section that depends from said belt. The lower edges of the panels 12 and 73 are .slidably interconnected with the adjacent belt of the next lower casing or housing section 61 to provide for free expansion and contraction of each tubular section with respect to the others.

The chains 33 of the bucket elevator or conveyer mechanism 34 are guided in the casing or housing 40 by a plurality of trough-like members 80, there being two such guide members on each of the panels 13, one for the working run and one for the return run of each chain.

The foot section 41 of the housing or casing 4!! involves important details of construction. Foot section .4! includes a feed chute 48 by which hot clay or other material to be elevated is delivered directly to the buckets 35 at the bottom of the feed run of the conveyer mechanism 34. The foot section or part 41 also includes structure providing gas-tight dust and heat seals which guide or limit the direction of movement of the foot shaft 31 which, as hereinbefore mentioned, is mounted for substantial free vertical or floating movement in a vertical plane through a limited 7 Referring particularly to Figs. 4 and 5 of the V drawings which illustrate structure which is duplicated on each sideof the elevator, it will be seen that the housing or casing 40 in this section in-- cludes a steel or metal side plate 50 which is attached to the adjacent portion of the main frame or tower 2B. Rigidly attached to the side plate 59 and forming a lining for this portion of the casing or housing 40 is a heavy plate of insulating material 5| which is the same in texture as the insulating material used throughout the head section 4! and most of the casing 48 to provide an insulating lining therefore The metal plate 50 and the insulating material 5! are provided with a vertical elongated slot 52 which is provided with a metal frame 53 rigidly attached to the plate 50 as by welding. The foot shaft 31 extends through the slot 52 and frame 53 and is mounted to move bodily only in a vertical direction therein. On the outside of the plate 56 and adjacent the slot 52 is a stationary box struc-' ture 54 which is formed by a pair of spaced vertical angle members 55 (see Fig. which are rigidly attached to the plate 50 by appropriate bolts.

Riveted to the angle members 55 and extending across the outer free ends thereof is a U shaped cover plate 55. Both the top and bottom of the cover plate 55 are provided with angle members which extend between the upright angle members 55 and are rigidly connected thereto as well as to the plate 50 and the cover plate 56. The bottom of these angle members is seen at 51 in Fig. 4 of the drawings. It is thus seen that the angle members 55 and 51 and the U-shaped cover plate 56 cooperate to provide an enclosing sta tionary box adjacent the slot 52 and this stationary box is provided with an elongated slot, similar to the slot 52, which is defined by a border frame 58, which frame member 58 is rigidly attached thereto as by screws and includes a central elongated slot 59, which slot 59 is somewhat wider than slot 52 (see Fig. 5).

Mounted on the foot shaft 31 to move upwardly and downwardly therewith, while at the same time providing for free rotation of shaft 3! with respect thereto, is a rectangular plate 50' of insulating material, similar to the material 5|, which is rigidly attached to a shiftable steel or metal plate (H which has a rigidly attached frame 52 which frames the insulation plate 53 and helps to hold it rigid with the steel plate BI. The composite shiftable plate 5U-5I is mounted for sliding movement within the aforedescribed box 54 formed by angle members 55 and 5'! and cover plate 56. In cooperation with the side plate 50 means are provided so asto effect a substantially continuous insulating wall to seal the slot 52 for all positions of adjustment of the shaft 31. To this end the inner periphery of the frame member 58 is provided with a continuous groove which carries and supports a pair of continuous strips of gasket material 63 against which the steel plate 5! continuously bears and has a sliding relation, thus providing an effective seal along this line of contact while permitting free sliding movement of the composite plate 5li-5l.

Furthermore, the steel plate 5| extends around its entire periphery beyond the insulation plate 5i} and the frame 62 and provides abutment or hearing areas for a plurality of coil springs 64 which are received by spaced guide posts 65 welded to a floating rectangular frame 65 made from an angle member which is bent or otherwise formed in a rectangle. The bottom of said frame 56 has frictional sliding contact with the side plate 50, the outwardly extending flange of which overlaps the frame 62 so that as the composite plate 6I62 moves up and down, it will carry the floating frame 65 held in frictional contact with the side plate 50. The overlapping flange of the frame 55 has a relatively close fit with the frame 62 so as to provide an effective seal therewith, though there is suificient clearance between the two to provide for their relative movement along a horizontal axis. It is therefore seen that there is a double seal between the slot 52 and the atmosphere, one seal being provided by the cooperation of floating frame 63 with the side plate 5!? and with the frame 62, the other seal being provided by the insulating strip 63 in cooperation with the steel plate BI. The apparatus which provides the gas-tight heat and dust seal above described, is claimed in my Patent No. 2,384,189, dated September 4, 1945, entitled Elevator.

Attention is now directed particularly to the structure of the foot shaft assembly 38 and the mechanism for mounting the foot shaft 31 for vertical adjustment in the slots 52. The structure illustrated in Fig. 4 is duplicated on each side of the unit.

The foot shaft assembly 38 includes at each side a traction wheel 39. and each wheel 39 includes a hub I33 and a plain ring type rim I34, the hub and rim being split, and each assembled and clamped to the shaft 3'! by a pair of bolts, not shown. Interconnecting the hub I33 and rim I34 is a plurality of yoke type spokes I31. Spokes I3! extend from the hub I33 to the rim E34 and each is oiiset from the radial to provide for relative expansion between the hub I33 and the rim I34. To aid in this expansion the opposite ends of each spoke it? are pivotally attached to the hub I33 and rim I34 by rivets I38 and I39, respectively. Should the ring I34 expand under the influence of heat in the casing 45! .it will be free to do so and the spokes I3! will swing about their pivot points and move toward a radial position. Conversely, should the rim I 3 3 contract, the spokes I3? would move farther away from the radial position.

The construction provided is such as to compensate readily for wide temperature variations to which the wheel 38 is subjected and to take care of the fact that shaft 31 is cooled while the rim I34 is very hot while the conveyer is in operation. The hub I33 and the major portion of each of the spokes I3! are embedded in a drum of insulating material I as which is built up of a plurality of axially separable sections held together by longitudinal tie bolts MI. The drum I45 is also split along a plane passing through the axis of shaft 31, the parts being held together by tie bolts, not shown.

Each end of the shaft 3'! extends through a round hole in the insulation plate and the at tached steel plate BI, as previously described, and a stufiing box I42 is attached to the plate 5| which provides a seal between shaft 3i and said steel plate 5I adjacent this opening. Stufiing box I42 slides in the slot 59 in border frame 58 for guiding the shaft in a vertical plane as set forth. Each end of shaft 31 is supported in a journal bearing I43 which is of the totally enclosed type and which is mounted in a beam I44. There are two beams 44 on opposite sides of the casing 48 and each extends parallel to and between the main frame side channels 2! and aside of the casing or housing of the foot section 41. Beams I 44 constitute the two side members of a box-like frame I45 (see Figs. 1, 2 and 3), the structure of which is described more completely hereinafter.

To cool the bearings M3 the shaft is hollow and there is a fitting I45 adjacent each end thereof which is received in a collar I4! clamped to the shaft 31, there being a packing ring and associated packing gland I43 to provide a water seal between the cylindrical outer surface of the fitting M6 and the collar I47, as well as with the rotating shaft 3 The fitting i id is stationary and is supported by a bracket M9 which con nected to the beam I64. Connected to the fitting 46 is a pipe Hit, the outside surface of which is spaced inwardly from the bore I5I of the hollow shaft 3?. Cooling water feed elbow i552 is connected through fitting I45to the interior of pipe I50 and water discharge elbow I53 is connected 7 by fitting I46 to the passageway formed on the outside of the pipe I50 and the surface of bore .Il.

The two pipes I50 which extend from opposite sides of the assembly 38 are connected together by pipe I54 which is provided with radial bores I55 providing ports to permit the feed water on the interior of the pipes I50 to flow outwardly into the return passageways between the outside of pipes I50 and the inside of hollow shaft 31. A brass helix I56 surrounds each pipe I50 and is rigidly attached thereto and spaced a very small amount from the wall of bore I5I to provide an elongated helical path for the cooling water.

In view of the great height of the elevator there will be an exceedingly heavy load on the head shaft 30 and on the links of chains 33 in the upper portion of the conveyer mechanism 34 since they must support the weight of substantially the entire conveyer mechanism 34. In order not to increase this load further, the frame I45 and the foot shaft assembly 38 is substantially counterbalanced, that is, the frame I45 is overbalanced for support a large portion of the weight of the foot shaft assembly 38.

Attention is now directed to the structure of the frame I45 and associated mechanism which provides for counterbalancing weight of the vertically floating foot shaft assembly 38. As seen in Fig. 3, the box-like frame I45 surrounds the foot section 41 of the casing or housing 40, and its side beams I44 extend between the interconnected pairs of side channels 21 and the sides of the foot section 41, The opposite ends of shaft 31 are solidly connected to the side beams I44 through the journal bearings I43 and thus as the foot shaft assembly moves in a vertical plane by reason of changes in the lengths of the chains 33, the frame I45 follows the movement of the shaft 31. The box-like frame I45 is pivotally mounted at its rear through a shaft which forms two axially aligned pivot points I51, said pivots I51 being mounted in rollers which roll between horizontally disposed top and bottom guides I53 that are integral parts of the main frame 20. consequence, as the shaft 31 moves in its vertical plane the frame I45 pivots about said pivots I51 and they move in a horizontal plane intersecting the vertical plane of movement of the shaft 31 to provide or permit vertical or rectilinear instead of arcuate travel of the shaft 31. It is, of course, evident that the axis of the pivot shaft and consequently the axis of the pivots I51 is parallel with the axis of shaft 31 and that it will remain so at all times.

Any of various means may be utilized for counterbalancing weight of'the frame I45 and foot shaft assembly 38 or for overbalancing the frame I45, but I prefer the winch mechanism shown in the drawings which includesa counterbalancing'weight I6I preferably mounted in a housing I62 and suspended from one or more cables I63 which is reeved over a pulley I64 which may be hooked to any frame structure and attached to a double diameter drum I65. Two suspension cables or rods I66 extend from the small diameter of the drum I65 to loops or bolts on the free end of frame I45. The double cylindrical drum I65 operates as a moment multiplier to reduce the necessary weight of the counterbalancing weight I6I. It is also desirable to indicate the position 0 the frame I45 and, as a consequence, of the shaft 31 in slot 52. To this end one of the frame beams is provided with a pointer I59 which cooperates with a stationary scale I60 attached to the main frame 20 and indicates the position of the frame I45 and foot shaft 31.

In the operation of the conveyer or elevator shown, hot material, such as clay or fullers earth, is fed to the feed chute 43 and by it directly into the buckets as they travel upwardly from the foot shaft assembly 38 along their working or elevating run. As the buckets 35 travel over the head shaft assembly 3| they discharge into discharge chute 42.

It is not uncommon for the temperature within the casing or housing to rise to 1000 degrees Fahrenheit and because of thishigh temperature and changes of temperature within the casing or housing the lengths of the chains 33 of bucket elevator mechanism 34 will vary, that is, as the temperature increases the chains expand and consequently the foot shaft assembly 38 descends, and as the temperature within the casing or housing decreases the chains 33 contract and lift the foot shaft assembly 38 in a vertical plane.

Provision has been made for guided free vertical or floating movement of the foot shaft which may be caused by changes in temperature within the casing or housing and consequently by changes in the temperature of the conveyer chains, or by wear of the conveyer chains 33. This has been accomplished by providing heat and dust seals that seal the foot shaft to the foot section 41 of the casing or housing and that guide, limit, or restrict the floating movement of the foot shaft to a plane. X

It will be seen that as the foot shaft moves in its guided path that the frame I45, the side memhers I 44 of which are solidly pivoted to it through journal bearings I43, follows the movement of the shaft. Because the rear end of the rectangular frame I is pivoted about the axis of the pivot points I51, which axis moves in a plane that intersects the vertical plane of movement of shaft 31 and the rear pivot axis always remains parallel to the vertical plane and the axis of shaft 31, the frame I45 functions as a lever, upon the free end of which a counterbalancing weight I6I acts. It is, of course, obvious, that because the frame I45 is a first class lever it cooperates with the double diameter drum I to maintain the necessary weight of counterbalance weight I6I at a minimum. The amount of the weight of the foot shaft assembly borne by the chains 33 may be varied by changing, for example, the weight of weight I6I, the diameters of double diameter drum I55, or the length of the lever arm or frame I45.

From the foregoing description it will be seen that I have provided an improved mechanism for counterbalancing weight of a foot shaft or foot shaft assembly wherein the foot shaft always moves in a plane and a portion or all of the weight of the foot shaft assembly thatcarries the conveyor chains may be counterbalanced to relieve the chains of undesired load.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore wish. not to be restricted to the precise construction herein disclosed,

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In an elevator, a housing, a power driven head shaft and wheel assembly within said housing adjacent the top thereof, an idler foot shaft and wheel assembly within said housing adjacent the bottom thereof, endless chain conveyer means within said housing operating over said head and idler foot assemblies, guide means in said housing guiding said chain conveyer means between said head and idler foot assemblies, means guiding said idler foot assembly for movement along a rectilinear path in an upright plane, a frame having opposite side members each carrying one end of said idler foot assembly through a bearing fixed thereto, means mounting one end of each of said opposite frame members for pivotal movement about a generally horizontal axis movable in a plane intersecting said upright plane, a counterbalancing mechanism for counterbalancing said frame and a portion of the weight of said idler foot assembly whereby load and wear on said chain and head assembly are materially reduced, said counterbalancing mechanism including a weight operated. winch, and indicator means associated with said frame indicating the elevational position of said idler foot assembly.

2. In an elevator, a housing, a power driven head shaft and wheel assembly within said housing adjacent the top thereof, an idler foot shaft and wheel assembly within said housing adjacent the bottom thereof, endless chain conveyor means within said housing operating over said head and idler foot assemblies, guide means in said housing guiding said chain conveyor means between said head and idler foot assemblies, means guiding said idler foot assembly for movement along a rectilinear path in an upright plane, a frame having opposite side members each carrying one end of said idler foot assembly through a bearing fixed thereto, means mounting one end of each of said opposite frame members for pivotal movement about a generally horizontal axis movable in a plane intersecting said upright plane, and counterbalancing mechanism for counterbalancing said frame and a portion of the weight of said idler foot assembly whereby load and wear on said chain and head assembly are materially reduced, said counterbalancing mechanism including a weight operated winch.

3. In an elevator, a housing, a power driven head shaft and wheel assembly within said housing adjacent the top thereof, an idler foot shaft and wheel assembly within said housing adjacent the bottom thereof, endless chain conveyor means within said housing operating over said head and idler foot assemblies, means guiding said idler foot assembly for movement along a rectilinear path in an upright plane, a frame having opposite side members each carrying one end of said idler foot assembly through a bearing fixed thereto, means mounting one end of each of said opposite frame members for pivotal movement about a generally horizontal axis movable in a plane intersecting said upright plane, a counterbalancing mechanism for counterbalancing said frame and a portion of the weight of said idlerfoot assembly whereby load and. wear on said chain and head assembly are materially reduced, said counterbancing mechanism including a weight operated winch, and indicator means associated with said frame indicating the elevational position of said idler foot assembly.

4. In an elevator, a housing, a power driven head shaft and wheel assembly within said housing adjacent the top thereof, an idler foot shaft and wheel assembly wihin said housing adjacent the bottom thereof, endless chain conveyor means within said housing operating over said head and idler foot assemblies, means guiding said idler foot assembly for movement along a rectilinear path in an upright plane, a frame having opposite side members each carrying one end of said idler foot assembly through a bearing fixed thereto, means mounting one end of each of said opposite frame members for pivotal movement about a generally horizontal axis movable in a plane intersecting said upright plane, and counterbalancing mechanism for counterbalancing said frame and a portion of the weight of said idler foot assembly whereby load and wear on said chain and head assembly are materially reduced, said counterbalancing mechanism including aweight operated winch.

STANLEY M. MERCIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 184,552 Smith Nov. 21, 1876 232,577 Walling Sept. 21, 1880 715,449 Willson Dec. 9, 1902 1,621,474 Blomfield Mar. 15, 1927 2,102,317 Gwinn Dec. 14, 1937 2,175,834 Fatkin Oct. 10, 1939 2,202,882 Wylie June 4, 1940 2,394,638 Schrader Feb. 12, 1946 2,433,697 Hulse Dec. 30, 1947 

